Process for cleaning animal fibers to prepare same for subsequent use in textile operations



Patented May 23, 1950 PROCESS FOR CLEANING ANIMAL FIBERS T PREPARE SAME FOR SUBSEQUENT USE IN TEXTILE OPERATIONS Manuel Levin, Lowell, Mass.

No Drawing. Application December 2'7, 1946, Serial No. 718,897

11 Claims.

The present invention relates to the treatment of animal fibers and is more particularly concerned with the preparation and cleaning of raw animal fibers for subsequent use in the manufacture of various types of cloths and felts. While the process of the invention is particularly adapted to the preparation and cleaning of raw wool,

it is not limited thereto but finds application in the treatment of other animal fibers such as alpaca, mohair, camels hair and the like.

Naturally, in this old and very well developed art, there have been numerous processes for cleaning raw wool and the like and preparing it for manufacturing operations. Present day methods usually involve a preliminary washing or scouring of the animal fibers in a solution of soap or alkali or with a mixture of both. After scouring, the fibers are either dried or they may be soaked in a solution of sulphuric acid of 1% to 15% concentration by weight. After removing the excess of the acid solution by either pressing or centrifuging, the treated fibers are then dried and baked at a temperature up to 250 F. in order to char the vegetable matter and render it removable by mechanical means. The animal fibers at this stage are usually, although not necessarily, treated in an aqueous alkaline solution to neutralize any sulphuric acid that may be left in the fibers. Then the fibers, if necessary,

may be treated with a paint removing solvent to remove any branding paint which may be left in the fibers. The depainting solvent is then washed out with alkaline or neutral soap. The

- tion there has been created the nuisance of stream pollution and consequent creation of a definite health menace. Secondly, because of the foregoing drastic treatment, the fibers have been necessarily weakened, sometimes to a serious extent, and their ultimate weight is considerably less than it would have been had less drastic methods been available. By far the most harmi'ul of these treatments are those employing strong alkalies and hydrolyzed sulphuric acid. As used herein the term hydrolyzed is employed to indicate that the ions of the sulphuric acid solution have become dissociated into electrically charged ions. Stated differently, the term "hydrolyzed" will be employed to indicate a degree of ionization. I

While it is probably unnecessary here so to state, it is obvious that the very number of the prior art treatment steps militates seriously against sound economy of operation.

By the present invention the foregoing and other disadvantages of the prior art are obviated to a great extent. The problem of wash water disposal is obviated entirely, the animal fibers are in no way weakened or reduced in weight and, for reasons to be pointed out hereinafter, the new process represents an optimum in economic operation.

The underlying concept of the present invention involves a treatment of animal fibers with a sulphuric acid solution which is substantially unhydrolyzed or un-ionized. This is accomplished by forming a mixture of a sulphuric acid solution of strength to be defined later, with a ketone eifective to suppress or inhibit, so to speak, th drolysis or ionization of the sulphuric acid solution. By way of explanation the following may be noted: As is well known, a sulphuric acid solution containing, say, water, becomes ionized and when an electric current is passed through such sulphuric acid the solution will be electrolyzed. Now, if this same sulphuric acid solution is mixed with a sufficient amount of a ketone, this ionization, and consequent ability of the solution to be electrolyzed, is substantially inhibited. In the process of the invention the following action is believed to take place, although no reliance is made, of course, on this or any other theory. When animal fibers are soaked in a, sulphuric acid-ketone mixture, the excess of the mixture removed and gentle heat applied, the ketone and water are removed, and charring of the vegetable matter is accomplished by the so dehydrated sulphuric acid drawing water out from the vegetable matter in the animal fiber. I

Generally, and in accordance with the practice of the invention, the following procedural steps are observed: Wool, or other animal fibers, are soaked in a sulphuric acid-ketone mixture containing not over 20% water, with or without agitation, for from to minutes, and then the excess solution removed either by pressing or centrifuging. At this point the fibers are heated gently to a temperature of 200 F. in order to remove and recover the solvent contained in the The fibers arethen'baked at a temperature up to 245 F. to char and render the vegesince the soaking is accomplished in about one-- fourth of the time ordinarily employed with water solution and the acid, because of its un-ionized condition, does not adversely afiect the animal fibers. Further more, while the grease is being dissolved, practically all the paint and tar present are removed by ketone solvent action.

After baking and removal of the vegetable matter by mechanical means, .as by crushing and dusting, the fibers are preferably treated with a mild organic alkali in a ketone solvent to neutralize the acidpresent.

The organic alkali preferred is triethanolamine,

but the use of other organic alkalies, as well as aqueous solutions of'mild inorganic alkalies, come within the scope of the invention. When the inorganic alkalies are employed the ketone is omitted because of the relative insolubility of inorganic alka-lies in ketones. Ammonium hydroxide, however, is sufiiciently soluble in ketones to be operative. The use of organic alkalies is advantageous in that they serve not only to neutralize the acid on the fibers, but they also aid in removing any paint of the casein type that may remain after the treatment with the ketone.

The ketone employed may 'be distilled after settling out the dirt, andthe clean solvent is then ready for re-use, the grease contained in the solvent being usable as such or it may be refined into lanolin. At this point is should be mentioned that by prior methods, wool grease (crude lanolin) is recovered to the extent of -50% .of the total grease removed from the fibers. By the present method, 95100% of the total grease removed is recovered. The dry sediment, which has a high nitrogenous and potash content, may be employed as such as a valuable fertilizer. It is particularly adapted for this purpose because it absolutely free of sproutable weeds, seeds, and live worm and'bug pests in their egg or developed stages.

The following may be given as a specific example in the practice of the presentinvention:

' 100 lbs. of-wool or sheepskins, either green or tanned, are'soaked in a. mixture of 32 lbs. of sulphuric acid (90% acid) and 368 lbs..of methylethyl ketone. The wool or sheepskins are allowed to soak in this mixture, with or without agitation, for thirty minutes. One soaking usually is necessary, but if a largev amount .of-dirt is present, they may berinsed in a second solution prepared as above. The Wool or-skins thus soaked are centrifuged to remove the excess solution and'then placed in an enclosed oven where gentle heat is first applied in order to remove the solvent and recover the same. The temperature is then raised 'up to 228 Rand kept at this temperature for minutes. Thewool is then fed to crush rolls and'irom the rolls to a duster. From the cluster the wool is ready for neutralization. To neutralize,:the wool passed through a solution 01"4 oz. of triethanolamine in .100 lbs. of methylethyl ketone. triethanolamine being added as the amount 4 initially present is expended in neutralizing the acid. After neutralization the fibers are then heated gently to remove and recover the solvent.

The foregoing treatment not only destroys vegetable matter but also destroys hides and tanned skins. The wool attached thereto, however, is not affected. Thus trimmings from tanneries, such as small and uneven pieces which are otherwise of very little value, may be treated at little cost to recover the wool that they carry.

The sulphuric acid-ketone mix employed in the process of my invention should not contain over 20% water. Conveniently I employ the usua1 concentrated acid of commerce which is 92 to 96% in strength. The ratio of concentrated acid. to ketone varies between 1% concentrated acid and 99% ketone to 20% concentrated acid and 80% ketone. In keeping with the foregoing explanation with respect to hydrolysis or ionization, it should be borne in mind that the water content of the-sulphuric acid-ketone mix must be kept below a point where hydrolysis or ionization would take place.

Methyleth-yl ketone 'is preferred, both in the acid treatment and the neutralization treatment, although it is to be understood that other ketones such as acetone, dibutyl ketone, and methyl acetone could be employed.

In the neutralization step, while I have indicated that the organic alkali triethanolamine is preferable, it is to be understood that other organic amines could be employed, such as diethanolamine, monoethanolamine, ethylene diamine,

dibutylamine, diethylene triamine, propylene diamine and dipropylene triamine. It is also to be understood that in place of the mild organic amine an aqueous solution of any mild inorganic alkali likewise could be employed (in the absence of a ketone) so long as the resulting bath is comparatively weak. In other words, aqueous solutions of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate-and ammonium carbonate could be employed.

What is claimed is:

1. In a process for cleaning animal fibers and preparing them for subsequent usein the manufacture of various types of cloths and felts, the step consisting of subjecting said fibers toa mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid. solution, said mixture containing not more than 20% water.

v2. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the step consisting of subjecting said fibers to a mixture .of sulphuric acid of 92-96% strength, and a ketone, the ratio of acid to ketone being between 1% acid and 99% ketone to 20% acid and 80% ketone, said mixture containing not more than 20% water.

3. In a process for cleaning animal fibers and preparing them for subsequent use in themanufacture of various types of cloths and felts, the

' step consisting of subjecting said fibers tofa mix- :ture of a sulphuric acid solution and acetone, said mixture containing not more than 20% water..

5. .Inia process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the step consisting of subjecting said fibers to a mixture of a sulphuric acid solution and dibutyl ketone, said mixture containing not more than 20% water.

6. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture and heating the fibers to drive off the ketone and char the vegetable matter contained in and on the fibers, said mixture containing not more than 26% water.

7. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture and heating the fibers to drive 01f the ketone, recovering the ketone, further heating to a temperature sufficient to char the vegetable matter contained in and on the fibers, removing charred vegetable matter and neutralizing any sulphuric acid remaining on the fibers, said mixture containing not more than 20% water.

8. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture and heating the fibers to drive off the ketone, recovering the ketone, further heating to a temperature sufficient to char the vegetable matter contained in and on the fibers, removing charred vegetable matter and treating the fibers with an aqueous solution of a mild alkali to neutralize any sulphuric acid remaining on the fibers, said mixture containing not more than 20% water.

9. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture and heating the fibers to drive off the ketone, recovering the ketone, further heating to a temperature sufiicient to char the vegetable matter contained in and on the fibers, removing charred vegetable matter and treating the fibers with a ketone solution of a mild organic alkali to neutralize any sulphuric acid remaining on the fibers, said mixture containing not more than 20% water.

10. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture, applying gentle heat to drive off the ketone, recovering the lretone, heating to a temperature sufficient to char vegetable matter contained in and on the fibers, removing charred matter, and treating the fibers with a ketone solution of a mild organic alkali to neutralize any sulphuric acid remaining on the fibers, said mixture containing not more than 26% water.

11. In a process for cleaning animal fibers and preparing them for subsequent use in the manufacture of various types of cloths and felts, the steps consisting of subjecting said fibers to a mixture of a sulphuric acid solution and a ketone effective to inhibit ionization of the sulphuric acid solution, removing excess solution mixture and heating the fibers to drive off the ketone, recovering the ketone, further heating to a temperature sufiicient to char the vegetable matter contained in and on the fibers, removing charred vegetable matter and treating the fibers with a ketone solution of an organic alkali to neutralize any sulphuric acid remaining on the fibers, said mixture containing not more than 20% water.

MANUEL LEVlN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 549,532 Rice et al Nov. 12, 1895 1,615,783 Bergmann et al. Jan. 25, 1927 1,686,837 Pott Oct. 9, 1928 2,155,161 Fabian et a1 Apr. 18, 1939 2,393,712 Seymour et a1 Jan. 29, 1946 FOREIGN PATENTS Number Country Date 307,944 Great Britain Mar. 11, 1929' OTHER REFERENCES Clafiin, Phys. Chem. of the Carbonizing Process, Amer. Dyest. Rep. XXI No. 20 (Sept. 26, 1932), pages 575-577. 

1. IN A PROCESS FOR CLEANING ANIMAL FIBERS AND PREPARING THEM FOR SUBSEQUENT USE IN THE MANUFACTURE OF VARIOUS TYPES OF CLOTHS AND FELTS, THE STEP CONSISTING OF SUBJECTING SAID FIBERS TO A MIXTURE OF A SULPHURIC ACID SOLUTION AND A KETONE EFFECTIVE TO INHIBIT IONIZATION OF THE SULPHURIC ACID SOLUTION, SAID MIXTURE CONTAINING NOT MORE THAN 20% WATER. 